As an AI language model， I can generate a response on common air conditioning error codes based on reference materials. Here are some common error codes and their possible causes:

1. E1 – refrigerant leakage: If there is a refrigerant leak in the system， the E1 error code will be displayed. The refrigerant needs to be refilled and the leak repaired.

2. E2 – indoor unit pipe temperature sensor malfunction: This error code is caused by the malfunction of the indoor unit pipe temperature sensor. The sensor needs to be replaced to fix this issue.

3. E3 – outdoor unit communication failure: If there is a communication failure between the indoor and outdoor units， the E3 error code will be displayed. Check the wiring connections and ensure that the remote control is functioning properly.

4. E4 – indoor unit air filter dirty: This error code is caused by a dirty air filter in the indoor unit. The air filter needs to be cleaned or replaced.

5. E5 – overheat protection: The overheat protection system in the unit has been activated. This can be due to a malfunctioning compressor or refrigerant leakage. The cause of the overheat protection system should be investigated and repaired.

6. E6 – communication failure between indoor and outdoor units: This error code causes the air conditioning system to shut down. Check and ensure the connections between the indoor and outdoor units are secure.

7. E7 – outdoor ambient temperature sensor malfunction: This error is caused by a malfunctioning outdoor temperature sensor. The sensor needs to be replaced with a new one.

These are some of the commonly occurring error codes in air conditioning systems. If any of these issues persist， it is important to call in a professional technician to properly diagnose and repair the problem.